Update formatting of gift card fields to be consistent on person page

[smarziano]

On a person's page, the formatting of the fields are different than what is currently on the /gift_cards "Recent sign-ups who need gift cards" page. The person page should be updated to be consistent.

• Switch the locations of the "Amount" and "Expiration Date" fields
• Update the styling of the expiration date format so that it matches what is on the Recent Sign-ups page so the " / " is automatically added